Collagen is a well known constituent of white fibrous tissue in animals. It is found in bone, cartilage and tendons, but particularly in cutaneous and subcutaneous connective tissue.
Methods for extracting collagen from tissue are well known. The preparation of an insoluble felt like collagen matrix is known as shown in U.S. Pat. No. 3,823,212.
While collagen support materials with a spongy or felt-like structure are already known, see U.S. Pat. No. 3,823,212, their denaturation temperatures are too low, or they cannot release natural soluble collagen (either in aqueous solution or on contact with the skin) since they are produced using highly reticulated chemical binding substances. When treated with these chemical binding substances, such as timing agents, natural collagen is irreversibly reticulated so as to bind any natural soluble collagen almost completely. The word reticulated used herein, as seen in the prior art, including U.S. Pat. No. 3,823,212 refers to the net-like, crossed-fiber network of the felt-like sponge. Furthermore, the presence of these binding substances, or of preservative substances, works against the main cosmetic purpose of treatment of dry skin. They may, in fact, be quite damaging to the skin itself.
Attempts have previously been made to solve this problem by using natural soluble collagen in oil/water emulsions, in aqueous or glycol solutions, or in other chemico-physical forms to be used either directly on the skin or by application on a reticulated collagen support at the moment of use. HOwever these products suffer from the severe disadvantage that collagen in solutions or emulsions has an extremely brief and often indeterminant life cycle due to its rapid denaturation. Therefore, the use of preservatives is required and efficacy is even then not reliable.
The following publications describe the techniques of preparing an insoluble collagen felt-like matrix:
K. H. Stenzel, T. Miyata, A. L. Rubin, Collagen as biomaterial Ann. Rev. Blophys. Bioeng., 3,231-253 (1974); U.S.A. Pat. No. 3,823,212; German patent No. 2625289;
A. Berg, H. Lindner, Schutz-proteine in der Kosmetik Parf. & Kosm., 60, 74-78 (1979); U.S. Pat. No. 4,193,813;
A. Berg, H. Dieringer, Collagen mask--Cosmetic Application & Analytical Control; Atti Congresso Naz. SICC., Milan 24-25 Nov 1983;
M. Chvapil, Z. Eckmayer, Role of proteins in cosmetics, Int. Journal of Cos. Science, 7, 41-49 (1985)
In the prior art, there is not cosmetic product based upon soluble collagen (such as emulsions, or aqueous or glycol solutions) which offers the guaranteed availability of a high concentration of natural soluble collagen, with its inherent chemico-physical behavior allowing complexation with other components and simultaneously having such stability.
Furthermore, the possibility of incorporating into the collagen matrix other cosmetically or pharmacologically active substances gives rise to the possibility of a product for local application to the skin which, in addition to its moisturizing effects, may also show therapeutic activity.